Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
2000-04-25
2001-09-18
Philogene, Pedro (Department: 3732)
Surgery
Instruments
Orthopedic instrumentation
C606S064000, C606S075000, C606S075000
Reexamination Certificate
active
06290700
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an apparatus for stiffening and/or correcting a skeletal structure or section thereof consisting of at least two bones or bone fragments, or a section of the spinal column consisting of at least two vertebrae, with at least two anchoring elements each of which can be attached to a bone or vertebra to receive a connecting element comprising a tensioning means in the form of a cable, wire or rod, which can be attached to the anchoring element, and spacer sleeves that can be slid over the tensioning means so that when a pulling force is exerted on the tensioning means, adjacent anchoring elements are kept a predetermined distance apart.
BACKGROUND OF THE INVENTION
An apparatus of this kind is known from WO 94/17745 in connection with the correction of a section of the spinal column. This known apparatus is characterized by high flexibility combined with long-term functional reliability. It can also be implanted by simple surgical techniques and allows subsequent adjustments of its positioning.
The object of the present invention is to improve the known apparatus with respect to its flexibility.
SUMMARY OF THE INVENTION
This object is achieved with an apparatus for stiffening and/or correcting a skeletal structure having at least two anchoring elements for a connecting element that has an elongate tensioning means and spacer sleeves. The spacer sleeves can be slid over the tensioning means in order to keep adjacent anchoring elements a predetermined distance apart when a pulling force is applied to the tensioning means. Each anchoring element is attachable to a bone or vertebra. Surfaces of the anchoring element against which the spacer sleeves abut are curved in a spherically convex or concave shape. As a result, it is possible for the abutment of the spacer sleeves against the associated anchoring elements to be adjusted to suit the direction of the tensioning means between two adjacent anchoring elements. Accordingly, it is not absolutely necessary for the tensioning means to be disposed at a predetermined angle with respect to the anchoring element. Instead, the operator can set this angle individually without being hindered by the spacer sleeves and their abutment against the anchoring elements.
Preferably the end surface of each spacer sleeve that faces an anchoring element is so formed as to be complementary to the supporting surface of the anchoring element, i.e. is spherically concave or convex. This measure ensures a large-area abutment of the spacer sleeves against the convex or concave curvature of the supporting surfaces of the anchoring elements.
An especially preferred embodiment of the apparatus in accordance with the invention is characterized in that the head of the anchoring element, which projects out of the bone or vertebra, is spherical in shape, in which regard it should be mentioned that the anchoring element can be either a pedicle screw or a pedicle hook. In the first case the head of the pedicle screw is a ball head.
So that the tensioning means can be fixed to the anchoring elements, the latter or their heads each comprise a passage, in particular a bore, with conical or trumpet-shaped, outwardly expanding openings through which the tensioning means is inserted or emerges. As a result, the tensioning means can enter or emerge from the anchoring element in an unconstrained manner, within a predetermined solid angle of 15 to 25 degrees.
In one advantageous embodiment the passage or bore is accessible over its entire length, either by way of a slot or by being openable, so that the tensioning means can be inserted into the passage in a direction perpendicular to the long direction of the passage. In both embodiments the anchoring element can first be fixed to the associated bone or vertebra. Only after this has been done is the tensioning means together with spacer sleeves attached to the anchoring elements. That is, in this embodiment the anchoring elements need not be threaded onto the tensioning means in advance. An especially simple embodiment is the first-mentioned, in which along the entire length of the passage in the anchoring element there is a slot through which the tensioning means is introduced. Alternatively, the anchoring element is constructed in two or more parts, such that the passage in the anchoring element can be opened over its entire length for insertion of the tensioning means. Thereafter the “lid” is replaced on the passage, so that the latter is closed radially on all sides.
The passages in the spacer sleeves preferably comprise entrance or exit openings that expand outward conically or in a trumpet shape, so that in the region where the spacer sleeves abut against the associated anchoring element, it is ensured that the tensioning means can run from the spacer sleeve into the passage through the anchoring element, and conversely, without constraint.
In another variant of the apparatus in accordance with the invention supporting balls that can be placed onto the tensioning means can also be provided, in particular balls slotted longitudinally, each of which can be inserted between two spacer sleeves in order to enable the distance between the anchoring elements to be altered or adjusted by placing in series two or more spacer sleeves of the same or different length. The said supporting balls each comprise a passage corresponding to the passage in the anchoring elements, to receive the cable-, wire- or rod-shaped tensioning means. The supporting balls are thus threaded onto the tensioning means, each between two adjacent spacer sleeves.
In order to increase versatility still further, it is conceivable to mount the part of each anchoring element that holds the tensioning means, in particular the ball head of a ball-head pedicle screw, so that it can rotate about an axis perpendicular to the longitudinal direction of the tensioning means, or about the long axis of the pedicle screw. As a result, the operator has an opportunity to adjust the tensioning means and the associated spacer sleeves in three dimensions, depending on the requirements of the individual case.
REFERENCES:
patent: 4950269 (1990-08-01), Gaines, Jr.
patent: 5042982 (1991-08-01), Harms et al.
patent: 5190543 (1993-03-01), Schlapfer
patent: 5683390 (1997-11-01), Metz-Stavenhagen et al.
patent: 5873878 (1999-02-01), Harms et al.
patent: 669109 (1995-08-01), None
Knobbe Martens Olson & Bear LLP
Philogene Pedro
Plus Endoprothetik AG
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